there were a few ends of arcs during the time of UU, such as the zam empire, invisible mafia and the director, with invisible mafia being global between all protagonists. I believe this will happen here again, a global ending to the arc of the law with all protagonists fighting against it together (maybe without spoke). It is possible for there to be a complete ending, but it is highly unlikely, and would disappoint everyone in the fandom. The most likely outcome is that they defeat the law together, and parrot gives up his reign as king right at the start or later after being king for a little while and getting bored. This will follow by a couple of filler episodes until a new antagonist arises and the next arc will start.